1. Field of the Invention
The present invention is related to human powered boats, and in particular to a boat which is powered by a helical drive mechanism.
2. Description of the Related Art
A conventional human powered row boat includes two oars which extend from the sides of the boat. The user lowers the oars into and drives the oars against the water to propel the boat during a power stroke. On the return stroke, the user raises the oars out of the water and moves the oars back to a position so that a power stroke can be re-initiated.
Therefore, the ends of the oars travel into and out of the water in an oval-shaped path. Thus, the user is forced to perform a rather awkward motion to move the oars. Furthermore, the user is forced to exert energy to the lift the oars out of the water on the return stroke.
A conventional human powered paddle boat includes two pedals which extend in front of and/or below the user's seat. The user drives the pedals in a rotary motion similar to driving a conventional bicycle. The motion of the pedals provides a force to a power transmission mechanism for propelling the boat.
Inherent in the rotary motion of each pedal are dead spots. Such dead spots occur when the pedal is closest and furthest from the main body of the user. When each pedal is in either of these two dead spots, a constant torque cannot be maintained, and therefore, a constant force cannot be provided to the power transmission mechanism from each pedal.
As disclosed in U.S. patent application Ser. No. 08/711,982 (the '982 application), a helical drive mechanism allows the user to drive the pedals in a rectilinear fashion, and thus, provides a constant torque to the power transmission mechanism. Therefore, the helical drive mechanism enables the force input onto the pedals to be transferred more efficiently. Other structure, applications, functions, and advantages are discussed in detail in the '982 application and the above-identified U.S. provisional applications.